I thought i would update this thread with what i discovered should it be useful for this applkication or another with similar requirments.

Maxim produce a chip called the DG403. This is a dual purpose TTL driven analogue switch. There for it has normally open and noramlly closed isolated contacts in the DIP package. Send a 1 and one switch will open and the other will close. It has two type switch configurations in the package.

Alternatively, they produce the DG303 which has about 4 NC switches.

Personally i think the DG403 is the better device as it caters for NO or NC contact operations.

Hope its useful to someone.

Steve